- 學位論文
利用超臨界流體技術進行石油瀝青的分離之研究
Separation of Petroleum Pitch Using Supercritical Fluid Technology
摘要
台灣每年煉製百萬桶以上的原油，在輕沸物的部分包括汽柴油、C1~C3原料、C4~C6原料、基礎油等，都有相應具有價值的產品應用，但重沸物的製程終端副產物瀝青，每年產量達百萬噸，卻僅有道路柏油、石油焦、發電燃料等低單價的應用。人造碳材是一項高單價的應用材料，亦是高階科技、尖端設備的關鍵材料，介相瀝青是人造碳材的重要來源，如何從國內石油瀝青製得介相瀝青，是一項值得探討的課題。有鑑於此，本研究第一部分取得國內石油瀝青包括：重油裂解塔底油瀝青、輕油裂解塔底油瀝青、真空蒸餾塔底油瀝青、柏油瀝青等，進行分析方法之研究與建立，並以國際石油瀝青A240及煤焦瀝青ST-CTP之分析結果進行比較，篩選合適的國內石油瀝青料源作為介相瀝青研究之原料。建立新穎性雙偵測器膠體層析儀研究設備，並完成石油瀝青分子量、分量分佈及結構特徵之快速分析方法之探討，透過UV-RI串聯式雙偵測器應用於瀝青分析鑑定，顯示所建立之儀器及方法具有良好的穩定性與再現性，分析結果能夠作為介相瀝青篩選之參考。 第二部分探討PP6石油瀝青的純化方法包括：傳統溶劑進行石油瀝青溶解分離、溶劑分子量分割純化、超臨界二氧化碳石油瀝青萃取分離及次臨界二氧化碳反溶劑系統進行石油瀝青之沉澱分離等，並製備百克級批量的石油瀝青純化樣品，包括透過熱迴流溶劑溶解分離及500 ml高壓槽之超臨界二氧化碳萃取分離。在不同的純化方法中，石油瀝青樣品均達到分子量分佈窄化、均勻度提昇的效果。在溶劑溶解分離的探討中，發現不同的溶劑系統，造成PP6石油瀝青溶解程度的差異，進而影響到分離純化後石油瀝青樣品的分子量及分子量分佈，製備最均勻的固相石油瀝青樣品之溶劑系統為乙酸乙酯，其分子量達3571 g/mole、分子量分佈PDI為1.6，但回收率僅8.6%。超臨界二氧化碳萃取分離對於PP6石油瀝青之小分子組分具有較高的選擇性，在4500 psi、80℃超臨界二氧化碳條件下萃取的萃餘物之分子量為1054 g/mole、PDI為3.6、回收率為86.0%。探討具新穎性次臨界二氧化碳反溶劑系統進行石油瀝青之沉澱分離，可以成功將大分子量的石油瀝青組份沉澱出來，在25℃、1700 psi至3700 psi的操作條件下，製得分子量分佈達3.5之石油瀝青樣品；研究發現，石油瀝青沉澱物分子量隨壓力昇高而增加，推測在探討的次臨界二氧化碳反溶劑壓力範圍下，主要的影響因子為二氧化碳的溶解效應，石油瀝青中，中大分子量組份溶解量隨壓力而增加，使固相石油瀝青樣品分子量上昇。透過壓力的調控，能夠控制二氧化碳的溶解效應，進而控制固相石油瀝青樣品之分子量。 本研究第三部分針對國內石油瀝青熱縮聚合之探討，建立100ml及熱縮聚合設備、2000ml級熱縮聚合設備、碳微球索式萃洗設備等；以GPC分析分子量聚合情形、利用TGA量測碳產率、以偏光顯微鏡量測介相化比例，求得較佳的熱縮聚合條件，確認石油瀝青超臨界純化後之產物，進行熱縮聚合具有較高的介相瀝青產率。成功建立國內石油瀝青製備石油瀝青系介相碳微球之程序，與中鋼碳素商品，進行比較及碳材分析結果及產品物性與分析結果之關聯。將碳化及石墨化後的石油瀝青系介相碳微球產品塗佈於銅箔，進行鈕扣電池的組裝及電性測試，結果呈現較高的初次充電量，較高的初次不可逆電量，及較低的二次充電電量，顯示材料上存在許多不規整的缺陷，造成不可逆電量的增加，相關研究結果，將有助後續國內石油瀝青介相瀝青產品之開發與改良。
並列摘要
Over million barrels of crude petroleum are refined in Taiwan every year. The light end products such as gasoline, C1~C3 and C4~C6 raw material, base oil and etc., are valuable in the chemical industry. However, the heavy end by-product petroleum pitch with amount of million ton per year exhibits much fewer values. Most of them are used to be road asphalt or petroleum coke for furnace. Artificial carbon material is one of high added value applications of mesophase pitch. These carbon materials are used in high technology processes and advanced equipment unit parts. It would be worth to study how to produce mesophase pitch from petroleum pitch in Taiwan. In the first part of the research, we acquired petroleum pitch samples of different petroleum refinery process, such as residue fluidized catalytic cracking (RFCC) process, pyrolysis fuel oil (PFO) process, vacuum distillation unit (VDU) process, asphalt product etc. and used for the analysis method research. The standard petroleum pitch sample A240 and coal tar pitch sample ST-CTP are examined and compared with the petroleum pitch samples. A novel dual detector gel permeation chromatography system is set up. A fast analysis method of the molecular weight, polydispersity index and characteristic structure of petroleum pitch is established. The UV-RI dual detector analysis method for petroleum pitch samples exhibit good stability and reliability. The analysis results are able to give a good reference for petroleum pitch starting material selection and mesophase pitch fabrication. In the second part of the research, the purification processes for PP6 petroleum pitch including: solvent dissolution separation method, solvent fraction method, supercritical carbon dioxide extraction method and subcritical anti-solvent method are investigated. The molecular weight distribution of the purified petroleum pitch is successfully narrowed down in all studied methods. In the solvent dissolution separation process, different solvent type results different dissolution extent of PP6 petroleum pitch, which will directly affect the molecular weight and molecular weight distribution of purified petroleum pitch. The most uniform petroleum pitch sample of solvent dissolution separation process is obtained in ethyl acetate solvent system, which equips molecular weight 3571 g/mole, PDI 1.6, but 8.6% recovery. Comparing with solvent dissolution method, supercritical carbon dioxide (scCO2) extraction method exhibits high selectivity to the small molecular component of PP6 petroleum pitch. At 80℃ and 4500 psi scCO2 extraction condition, a residual of 86.0% high recovery with molecular weight 1054 g/mole and PDI 3.6 is obtained. A large vessel of 500 ml of scCO2 extraction is established. Hundred gram purified petroleum pitch sample for thermal condensation polymerization is able to be produced in single batch scCO2 extraction operation. A novel subcritical anti-solvent (SAS) precipitation separation method for PP6 petroleum pitch is studied in the range of 1700 psi to 3700 psi at 25℃. The molecular weight distribution of precipitated is successfully narrowed down to 3.5 in advance. The molecular weight is found to be increasing with increasing pressure in the SAS process, a higher solvent power of carbon dioxide at higher pressure is proposed to be the dominated effect. As a result, the molecular weight of precipitated petroleum pitch can be manipulated via pressure in the SAS process. In the third part of the research, the thermal condensation polymerization process of petroleum pitch is investigated. Thermal condensation polymerization equipment size of 100 ml and 2000 ml are established to investigate the experimental factor of petroleum pitch thermal condensation polymerization. Soxhlet extraction apparatus is established to isolate mesophase carbon micro bead (MCMB) from petroleum pitch thermal condensation polymerization product. We found that the petroleum pitch purified with supercritical fluid extraction will lead to a higher mesphase pitch yield. The petroleum pitch MCMB product synthesized in this study is analyzed and compared with commercial MCMB product. The product is going on proceeding carbonization and graphitization process and composed into a Li-ion coin cell. The measurement electrical properties show that there are higher first time charge density, higher first time irreversible capacity and lower secondary charge density. The more defect is proposed and can be observed by Raman spectrum to response to the electrical result. The material of petroleum pitch MCMB is successfully synthesized in this study and the analysis result will helpful to further improvement of this material.